For qualitative and quantitative analysis of components of a liquid sample, in particular of a body fluid from humans or animals, test methods working with test elements are used extensively. The test elements generally contain reagents. In order to perform a reaction, the test element is contacted with the liquid sample. The reaction between the liquid sample and the reagent leads to a change in the test element that is characteristic of the analysis, and this change is analyzed using a suitable analytical device. Typically, the analytical device is suitable for analysis of a specific type of test element from a specific manufacturer.
The test elements and the analytical device are mutually adapted components and, in combination, are called an analytical system.
Numerous different types of test elements are known which differ from each other by their measuring principle and the reagents that are used as well as by their structure.
With regard to the measuring principle, calorimetric analytical systems are particularly common. In these systems, the sample reacting with the reagents contained in the test element leads to a color change that can be measured visually or by means of a photometric measuring facility. Moreover, electrochemical analytical systems have gained great significance, in which the sample reacting with the reagents of the test element leads to an electrically detectable change (of an electrical voltage or an electrical current) that is measured with appropriate measuring electronics. Analytical systems of this type are also called amperometric systems.
In many cases, there is a need for regular monitoring of certain analytic blood values. This applies in particular to diabetics who should self-monitor their blood glucose levels frequently in order to maintain these levels within certain nominal limits (ideally, at all times) by suitably adapting their insulin intake via injections or other means to the strongly varying needs. Accordingly, the testing of blood coagulation parameters by patient blood coagulation self-monitoring is also quite common, as is self-monitoring of blood cholesterol levels.
A blood glucose measuring device is a measuring device that can be used for qualitative or quantitative determination of the blood glucose content. For this purpose, it is customary to generate a puncture wound in a body, draw a drop of blood, apply the drop of blood to a test element, and use the test element and the blood glucose measuring device to determine the blood glucose content or concentration of the drop. However, it is also conceivable to measure the blood glucose by means of a continuous measurement, for example with sensors introduced into the body or by a measurement through the skin.
Blood analysis systems should be easy to operate, compact and slim in design, and easy and cheap to manufacture. These practical requirements have led and are leading to the development of blood analysis devices that satisfy these, to some extent contradictory, requirements to the extent possible.
Especially in the area of so-called “home monitoring”, i.e. where medical laymen perform simple blood analyses, and, in particular, in the periodical drawing of blood several times daily by diabetics for monitoring of their blood glucose concentration, it is important to have a blood glucose measuring device that is easy and reliable to operate and to have an informative and reliable determination and display of the measuring results.
Conventional analytical devices are so-called stand-alone measuring devices. These devices operate autonomously, self-supporting, and independently. Accordingly, they comprise a display, a measuring facility, a power supply, and a complete user interface that can, for example, comprise a keyboard, a display, a triggering facility or a user guidance. The application purpose and properties of devices of this type are fixed with the exception of occasional adaptation of their firmware.
Approaches to modular concepts aiming to design the application range of these devices more versatile and to make them smaller and cheaper are available.
From document, WO 89/00024, a modular physiological measuring system is known, in which various specific measuring modules, for example an oxygen-measuring module or a blood pressure-measuring module, can be connected to a central unit. Recently, a comparable system for the determination of blood glucose has been developed, in which a blood glucose-measuring module is connected to a PDA.
However, these known systems have been found to be disadvantageous in that the technology of the central unit or PDA is subject to continual technical change by the manufacturers such that, due to non-standardized interfaces between the device and the connected measuring module being used and because of the ongoing changes of the hardware platforms, i.e. the further development of processors and protocols, each and every change made in the device requires that a new application for approval/registration of the measuring module for the medical application at hand had to be filed and be accompanied by proof of the operability of the device in combination with the central unit or PDA.
It is therefore desirable to create an analytical device that is very compact and can be used by an operator in particularly simple fashion.